Electrical Capacitance Tomography With Inner Electrode Array

Electrical Capacitance Tomography(ECT)is a more comparatively mature technology in process tomography(PT)which is based on capacitance sensing theory in electromagnetic field.Having the advantages of non-radiation,non-intrusive,simple configuration,rapid response,low cost,and visualization,ECT has broad application prospects for parameter measurement of multiphase flow in industrial process.In this thesis,the mathematical model and equivalent circuit of the capcacitance sensor structure,the optimal design of capacitance sensor with inner electrode array,the hardware design of system,the reconstruction algorithms and related techniques are studied.The main works in this paper are as follows:1.Analyzing the measureing principle of capacitance sensor of the ECT system,optimal design of the capacitance sensor with inner electrode array is carried out by factorial design experiment method and uniform design(UD)experiment design method,and the optimal parameters of the capacitance sensor structure are botained.A new capacitance sensor with rotating electrodes is proposed,and the simulation research and design are carried out.2.The data acquisition system(DAS)of ECT is studied and designed.And the properties of C/V circuit and switch gating ciucuit are studied mainly.ECT system is designed which using USB2.0 high-speed serial interface as the communication interface,the DAS with the FPGA as the core processor.Then,the software part for FPGA is programmed with the modularization design.3.Summarizing the reconstruction algorithm of ECT,the fast iterative shrinkage-threshold algorithm(FISTA)is analysed.A model for image reconstruction of ECT whith data term and regularization term are all l1-norm is proposed.And the new problem is solved by primal-dual interior point method(PDIPM).Simulation and experiment are conducted out for verifying the proposed algorithm.4.By using the capacitance sensor with inner electrode array,the static experiments of gas-solid two-phase flow related flow regime,the static experiments of the weakly conductive liquid-solid two-phase flow related flow regime and the oil-cut measurement experiments of uniform mixing oil-water two-phase flow are carried out.The results show that capacitance sensor with inner electrode array can broaden the measurement range correspondingly.